Research on the Development of Fibroin and Nano-Fiber from Silk Cocoons for Regenerated Tissue Engineering Applications by Electro-Spinning

In this paper, the main goal is to prepare silk fibroin nano-fiber, which is used for regenerated tissue applications. Silk scaffold nano-fibers made by electro-spinning technology can be used in regenerated tissue applications. The purpose of the research is to prepare a silk-fibroin nano-fiber solution for potential applications in tissue engineering. Using a degumming process, pure silk fibroin protein is extracted from silk cocoons. The protein solution for fibroin is purified, and the protein content is determined. The precise chemical composition, exact temperature, time, voltage, distance, ratio, and humidity all have a huge impact on degumming, solubility, and electro-spinning nano-fibers. The SEM investigates the morphology of silk fibroin nano-fibres at different magnifications. It also reveals the surface condition, fiber orientation, and fiber thickness of the silk fibroin nano-fiber. The results show that regenerated silk fibroin and nano-fiber can be used in silk fibroin scaffolds for various tissue engineering applications.

An energetic nano-fiber composite based on polystyrene and 1,3,5-trinitro-1,3,5-triazinane fabricated via electrospinning technique

Electrospinning is a simple technique used to fabricate polymeric nano-fibrous membranes.These nano-fibers have found a wide range of valuable applications in the biomedical field.However,it has not been utilized with solid high explosives yet.Herein,the electrospinning technique has been used to fabricate polystyrene(PS)/1,3,5-trinitro-1,3,5-triazinane(RDX)composite nanofibers.The governed electrospinning parameters,voltage,distance from the collector,flow rate,mandrel rotating speed,time,and solution concentration,that greatly affect the morphology of the obtained nanofibers were optimized.The fabricated PS/RDX nano-fibers were characterized using scanning electron microscopy(SEM),X-ray diffractometer(XRD),and Fourier Transform Infrared(FTIR)spectroscopy.The impact and friction sensitivities of PS/RDX were also measured.The thermal behavior of the prepared composite and the pure materials were studied by the thermal gravimetric analysis technique(TGA).SEM results proved the fabrication of PS/RDX fibers in the nano-size via electrospinning.FTIR spectroscopy confirmed the existence of the characteristic functional groups of both PS and RDX in the composite nano-fibers.XRD sharp peaks showed the conversion of amorphous PS into crystalline shape via electrospinning and also confirmed the formation of PS/RDX composite.The PS fibers absorbed the heat and increased the onset decomposition of the pure RDX from 181.5 to 200.7℃in the case of PS/RDX fibers.Interestingly,PS/RDX nano-fibers showed the relatively low impact and friction sensitivities of 100 J and 360 N respectively.These results could introduce PS/RDX nanofibrous composite in the field of explosives detection with high levels of safety.

Spectra of spontaneous Raman scattering in taper-drawn micro/nano-fibers

We study the spontaneous Raman scattering （RS） in taper-drawn micro/nano-fibers （MNFs） by employing the photon counting technique. The spectra of RS in five MNFs, which are fabricated by using different heating flames （hydrogen flame or butane flame） and with different diameters, are measured within a frequency shift range of 1435 cm- 1_3200 cm- 1. From the measured spectra, we observe the RS peaks originated from silica and a unique RS peak with a frequency shift of - 2905 cm-1 （- 87.2 THz）. Unlike the former ones, the latter one is not observable in conventional optical fibers. Furthermore, the unique peak becomes obvious and starts to rapidly increase with the decrease of the diameter of MNFs when the diameter is smaller than 2 μm, and the intensity of the unique peak significantly depends on the heating flame used in the fabricating process. Our investigation is useful for the entanglement generation or optical sensing using taper-drawn MNFs.

Effects of Ni catalyzer on growth velocity and morphology of SiC nano-fibers

Composite felts reinforced by both SiC nano-fibers(SiC-NFs)and carbon fibers were prepared at 1 273 K using Ni granules as catalyzers with different deposition time.SiC-NFs were deposited on the surface of the carbon fibers in situ by catalytic chemical vapor deposition(CCVD).The phase,microstructure and morphology of the fibers after electroplating and deposition were characterized by XRD,SEM and TEM.The results show that the SiC-NFs produced by CCVD are composed of single crystal of β-SiC.It is found that smaller nano-granules are more active as catalyzers.The resulting SiC-NFs appear more spindle-like and have a more homogeneous dispersion.The mass change of the samples before and after deposition shows that using more Ni granules results in a faster growth velocity of SiC-NFs.With the same electroplating time,the growth velocity of the SiC-NFs first increases and then decreases.At around 4 h,it reaches the maximum growth velocity,and it becomes nearly constant at around 8 h.After 8 h, the stable growth velocity of the electroplated Ni samples is faster than that of the conventional sample produced without catalyzers, because the SiC-NFs can improve the specific surface area and the activity of the surface.

Stability of partially deacetylated chitin nano-fiber dispersions mediated by protonic acids

Partially deacetylated chitin nano-fiber(DAChN)dispersions were prepared using mechanical treatment of partially deacetylated crab shellα-chitin under acidic conditions mediated by various protonic acids.The representative organic acids had a better efficiency in terms of mediating the nanofibrillation of chitin fibers in comparison to the inorganic acid(HCl).The DAChN dispersed in water at a pH of 3.5 mediated by gluconic acid exhibited the highest yield of nano-fibers(88.6%),followed by succinic,itaconic,and ascorbic acids with a nano-fiber yield of 79.9%,73.3%and 66.0%,respectively.The pH,conductivity,viscosity,and light transmittance of dispersions were assessed under different storage times.All of the tested DAChN dispersions were stable for at least 15 weeks at 4℃.

Dynamic effective elastic modulus of polymer matrix composites with dense piezoelectric nano-fibers considering surface/interface effect

Based on effective field method,the dynamic effective elastic modulus of polymer matrix composites embedded with dense piezoelectric nano-fibers is obtained,and the interacting effect of piezoelectric surfaces/interfaces around the nano-fibers is considered.The multiple scattering effects of harmonic anti-plane shear waves between the piezoelectric nano-fibers with surface/interface are averaged by effective field method.To analyze the interacting results among the random nano-fibers,the problem of two typical piezoelectric nano-fibers is introduced by employing the addition theorem of Bessel functions.Through numerical calculations,the influence of the distance between the randomly distributed piezoelectric nano-fibers under different surface/interface parameters is analyzed.The effect of piezoelectric property of surface/interface on the effective shear modulus under different volume fractions is also examined.Comparison with the simplified cases is given to validate this dynamic electro-elastic model.

高密度聚乙烯三维网状纳微米纤维的强伸性能

为实现高密度聚乙烯三维网状纳微米纤维(PENFs)的自主化规模化生产,以高密度聚乙烯和二氯甲烷为原料,通过高压闪喷纺丝设备成功制备了性能优异的PENFs,采用响应面法对纺丝过程中各工艺参数进行优化,并对其力学性能和耐候性能进行分析。结果表明:PENFs的最佳制备工艺条件为纺丝温度176.3℃、纺丝压力8.6 MPa、纺丝溶液质量分数8.0%,此时制得的PENFs的断裂强度和断裂伸长率分别可达到29.1 cN/dtex和99.9%,优于芳纶和涤纶等常规纤维;定伸长和定载荷条件下,PENFs的弹性回复能力随着拉伸次数和载荷的增加而逐渐降低,拉伸伸长为5%时PENFs纤维的弹性回复率可达到92.8%且拉伸10次后降低至75.5%,拉伸载荷为1.2 N时PENFs纤维的弹性回复率为84.6%;放置在室外20 d内PENFs纤维的强伸性能损失较小,30 d后断裂强度和断裂伸长率明显降低,但纤维外貌并无明显变化。

微纳化封装芳香载体的制备及缓释性能研究

芳香纺织品是备受关注的功能纺织品。芳香气味具有舒缓压力、调节情绪、改善睡眠等功效。但是芳香物质存在易挥发的问题,提高香味的长效释放和耐水洗性一直是芳香纺织品制备有待解决的问题。文中以硅烷偶联剂对纳米二氧化硅进行表面结构调控处理,构建有机-无机复合材料,探索芳香物质微纳化封装;将微纳化封装的芳香载体材料通过原位固定法负载到织物上,并对织物的芳香释放性能和耐久效果进行评价。结果表明,由微纳化封装的有机-无机复合芳香载体制备的芳香纤维结构体具有适宜的香气和长效释放的效果,由此形成的织物加香技术,可广泛应用于纺织品芳香整理,在芳香功能纺织品的制备应用中拥有巨大潜力。

复掺钢纤维-纳米炭黑混凝土力学性能的研究及优化

对复掺钢纤维-纳米炭黑混凝土进行立方体抗压试验、劈裂抗拉试验和抗折试验,并对试验结果进行极差分析、层次分析、因素指标分析和线性回归分析。结果表明:钢纤维类型对混凝土拉压比、折压比的影响最大;随着钢纤维质量分数的增加,混凝土拉压比和折压比均出现了先升高后下降的现象,纳米炭黑质量分数的增加对混凝土强度比没有显著的提升效果。在拉压比方面,混凝土最优配合比为钢纤维类型SF-A(剪切型),钢纤维质量分数0.40%、纳米炭黑质量分数0.75%;在折压比方面,最优组合为钢纤维类型SF-A(剪切型),钢纤维质量分数0.60%、纳米炭黑质量分数1.00%,并且得到的线性回归模型可以在本文所选取的范围内对折压比和拉压比进行预测。

静电纺聚酰胺6/聚苯乙烯复合纳米纤维膜制备及其空气过滤性能

针对空气过滤纤维材料的过滤效率、阻力和使用寿命难以平衡的问题,采用多喷头静电纺丝技术,制备了不同直径、形貌纤维及不同纤维沉积顺序的聚酰胺6/聚苯乙烯(PA6/PS)复合纳米纤维膜,测试了复合膜的平均孔径及孔隙率,建立了纤维结构与过滤效率及阻力的构效关系;结合扫描电镜表征探讨了不同形貌、直径纤维的叠加次序对过滤寿命及细颗粒物沉积行为的影响,系统研究了过滤风速、细颗粒物尺寸对过滤性能的影响。结果表明:在5.33 cm/s的风速下,以多喷头静电纺丝方式制备的PA6/PS复合膜具有更好的抵抗风速变化的能力,在长期使用中阻力增加较缓慢,其具有93.13%的过滤效率,30.67 Pa的过滤阻力和0.0889 Pa-1的品质因子,综合过滤性能优于同等条件下H10等级(过滤效率>90%)的商业玻璃纤维过滤膜。

导电微纳纤维复合纱的制备及其气敏特性

为开发高质量的气敏传感器,利用水浴静电纺丝法制备以涤纶(PET)为芯纱,聚酰胺6(PA6)纳米纤维为包覆层的微纳纤维复合纱(MNY),基于原位聚合方法对MNY进行连续导电处理,制备微纳米纤维复合纱/聚苯胺(MNY/PANI)复合导电纱,以此作为气敏元件,同时将相同参数下制备的PET/PANI复合导电纱也作为气敏元件进行对照,探究不同结构纱线之间气敏效果的差异。研究结果表明:MNY具备良好的皮芯结构,经导电处理后MNY表面均匀分布了聚苯胺颗粒,MNY/PANI的电导率最高可达7.53 S/cm;相比于PET/PANI气敏元件,MNY/PANI气敏元件因其纳米结构的高比表面积对NH 3的灵敏度更高,能表现出更好的响应-恢复效果,重复性和稳定性更好,已初步具备了作为优良气敏元件的条件。

拉伸法制备微纳光纤的设计与研究

微纳光纤通常采用光纤拉锥法制备.对原有装置进行改进,增加电机和控制器搭建火焰加热电机拉伸法制备微纳光纤的实验平台,实现了微纳光纤的自动化制备.探究了光纤直径与拉伸距离、拉伸速度、火焰高度等的关系.理论推导出单侧拉伸过程中锥区直径与拉伸长度的关系,通过对不同速度下锥区形状的测量,解释了拉伸速度影响光纤直径的原因.

溶液喷射纺丝参数对聚丙烯腈直径分布的影响

利用溶液喷射纺丝技术,成功制备聚丙烯腈纤维膜。采用扫描电镜观察纤维膜的形貌,探究不同纺丝工艺参数对纤维直径分布的影响。结果表明:纤维直径与聚合物质量分数、聚合物溶液挤出速度、喷丝孔内径呈正比,并且随上述工艺参数的增加,纤维直径分布较为离散;纤维直径与喷射气流的压强、接收距离呈反比,并且随上述工艺参数增加,纤维直径分布逐渐集中。经分析,获得最优工艺参数:聚合物质量分数为12%,喷射气流的压强为0.15 MPa,接收距离为70 cm,溶液挤出速度为0.3 mL/min,喷丝孔内径为0.32 mm。

细菌纤维素/羟基磷灰石@聚醚砜骨膜支架的制备及其性能研究

骨膜作为骨缺损修复过程中营养物质的来源及膜内成骨过程中的核心位点,其结构和功能的重建对大尺度骨缺损的修复起到极其重要的作用。基于此,为了模拟天然骨膜的结构和功能,将聚醚砜(PES)和羟基磷灰石(HAp)混合,通过静电纺丝制备HAp@PES静电纺纤维膜(HPES),然后通过膜液界面培养法与细菌纤维素(BC)复合,获得了具有微米―纳米结构的BC/HAp@PES(BC/HPES)支架。扫描电镜结果表明,该支架微米―纳米纤维交错分布,且HAp成功复合在微米纤维上。所制备的支架具有良好的力学性能。进一步研究表明,成骨细胞在支架表面表现出良好的增殖和铺展能力,不仅如此,该支架还具有良好的成骨分化诱导能力。因此,这种具有仿生微纳纤维结构且负载HAp的骨膜支架有望用于大尺度骨缺损修复领域。

碳纳米管质量分数对纳米芳纶复合气凝胶纤维电磁屏蔽性能的影响

为了研究碳纳米管(CNTs)的质量分数对纳米芳纶(ANF)复合气凝胶纤维的电磁屏蔽性能的影响。将CNTs与ANF分散在通过二甲基亚砜(DMSO)中,改变CNTs与ANF的比例。对复合气凝胶纤维的力学性能、导电性能、微观形貌、 X射线光电子能谱、红外光谱、热失重等性能进行测试,确定实验范围内的CNTs的最佳参数。结果表明:当CNTs在分散液中的质量分数达到25%时,复合气凝胶纤维的电磁屏蔽效能达到-18 dB。CNTs/ANF复合气凝胶纤维可以屏蔽80%的电磁波,满足工业要求。

纳米氧化锆/碳纤维改性环氧复合涂料的制备及其性能研究

为了提高环氧涂层在3.5%NaCl溶液中的耐腐蚀性能,延长金属的使用寿命,通过硅烷偶联剂KH560对纳米ZrO_(2)和碳纤维(Cnf)杂化,制备得到ZrO_(2)-Cnf。将原子分数1%,2%,3%和4%的ZrO_(2)和ZrO_(2)-Cnf 2种填料分别添加至环氧(EP)涂料中,通过喷涂法制备得到ZrO_(2)/EP涂层和ZrO_(2)-Cnf/EP涂层。通过扫描电子显微镜、傅里叶红外光谱、电化学测试、维氏硬度测试、摩擦磨损试验对改性填料和改性环氧复合涂料进行了表征。结果表明,改性后的填料可以充分提高环氧树脂涂层的耐腐蚀性能,当填料的含量为2%时,ZrO_(2)/EP涂层和ZrO_(2)-Cnf/EP涂层的耐腐蚀性能均最佳,磨损损失量最小;当2种填料的含量为3%时,硬度值最大,分别为32.9 HV5.0和46.6 HV5.0。

碳纤维对纳米偏高岭土再生混凝土抗折强度及微观结构影响试验研究

为了充分利用再生混凝土资源,采用碳纤维对纳米偏高岭土再生混凝土抗折强度进行改性,以不同碳纤维和纳米偏高岭土掺量作为变量制备再生混凝土,结合压汞法及扫描电镜研究再生混凝土孔隙结构及微观形貌特征,分析碳纤维对纳米偏高岭土再生混凝土的改性机理。结果表明:碳纤维对再生混凝土抗折强度增强效果显著,在不同纳米偏高岭土掺量下,碳纤维适配掺量有所不同,当纳米偏高岭土掺量为7%、10%、12%时,碳纤维最佳掺量分别为0.1%、0.15%、0.2%,当纳米偏高岭土掺量为10%,碳纤维掺量为0.15%时,抗折强度达到最大值,较普通再生混凝土强度增幅为59.1%;碳纤维的掺入细化了再生混凝土内部的孔隙结构,使有害孔和多害孔的比例降低,少害孔的比例增加;碳纤维在再生混凝土内部起到承载及阻裂作用,纳米偏高岭土的填充效应以及火山灰活性增强了界面过渡区的粘接强度,使碳纤维更能发挥其作用,进而促进再生混凝土强度的提高。

SiO_(2)/KH560改性玄武岩纤维混凝土力学性能研究

为了研究硅烷偶联剂(KH560)和纳米SiO_(2)协同KH560改性玄武岩纤维(BF)对混凝土力学性能的影响,本文采用KH560对BF进行表面改性,制得KH560-BF,并采用纳米SiO_(2)和KH560改性BF制得SiO_(2)-KH560-BF。通过正交试验筛选出高强度改性纤维,研究了纳米SiO_(2)分散液、润滑剂和KH560三者的质量分数对SiO_(2)-KH560-BF的丝束强度影响。采用SEM和EDS对改性混凝土的7和28 d的力学性能进行评估,并对混凝土的微观结构进行表征。结果表明,SiO_(2)-KH560-BF的最佳上浆剂成分为纳米SiO_(2)分散液1.6%、润滑剂0.4%和KH5600.5%,且三个因素的影响程度从大到小依次为纳米二氧化硅分散液、KH560、润滑剂。与KH560-BF相比,SiO_(2)-KH560-BF纤维丝束强度提高了8.62%,拉伸强度提高了4.41%,Si含量提升了24.9%,并且从SEM照片中可以看出SiO_(2)-KH560-BF团状堆积比KH560-BF少。掺入适量SiO_(2)-KH560-BF的混凝土7和28 d抗压、劈裂抗拉和轴心抗压强度提升效果均高于掺入KH560-BF的混凝土。

凝固浴牵伸对微纳层叠带状PAN原丝性能的影响

采用新型微纳层叠挤出技术制备了层叠带状聚丙烯腈(PAN)碳纤维原丝,利用扫描电子显微镜、X射线衍射仪、万能材料试验机和差示扫描量热仪对原丝的性能进行表征,研究了不同凝固浴牵伸倍数对微纳层叠带状PAN原丝截面形态、结晶性能、力学性能以及热行为的影响。研究结果表明,随着凝固浴牵伸倍数的提高,层叠带状PAN原丝的厚度显著减小,线密度显著降低;层叠带状PAN原丝的结晶度和拉伸强度随着牵伸倍数的提高呈现先增加后减小的趋势,凝固浴牵伸倍数为5.5倍时,获得的层叠带状PAN原丝的性能较好。当凝固浴牵伸倍数从5.5倍增加至6.5倍时,原丝的拉伸强度由26.08 MPa降低至23.36 MPa。实验结果表明,凝固浴牵伸倍数为5.5倍下制备的层叠带状PAN原丝具有较好的综合性能,其结晶度为39.1%,拉伸强度和拉伸模量分别为26.08及661 MPa。